WAS the name of the band the Roots played in the flick. they were in blackface, and they were dancing like Sambos. I remember a particular shot where Thought is grinning like an idiot and hopping around.
However, the other side of that story is that the film is a satire of what is going on in the media right now, the roles some black actors are playing and some of the garbage networks have been putting on TV.
So on the one hand, the film is a critique of this, not an endorsement of it. On the other hand, there are characters in the film who embrace the ignorance of the show and aren't shown to have remorse or second-thoughts about it. "The Alabama Porch Monkeys" seem to fall into this category. Then again, they don't have any lines.
So I don't think Nas was necessarily wrong in the criticism, but he made it sound like they were actually playing themselves, and not characters.